The reference configurations described in this paper are starting points for building Sun Customer Ready HPC Clusters configured with the Sun Fire X4100, X4200, and X4600 families of servers. The configurations define how Sun Systems Group products can be configured in a typical grid rack deployment. This document describes configurations using Sun Fire X4100 and X4100 M2 servers with a Gigabit Ethernet data fabric and with a high-speed InfiniBand fabric. In addition, this document describes configurations using Sun Fire X4200, X4200 M2, X4600, and X4600 M2 servers with an InfiniBand data fabric. These configurations focus on single rack solutions, with external connections through uplink ports of the switches. These reference configurations have been architected using Sun's expertise gained in actual, real-world installations. Within certain constraints, as described in the later sections, the system can be tailored to the customer needs. Certain system components described in this document are only available through Sun's factory integration. Although the information contained here could be used during an integration on-site, the optimal benefit is achieved through Sun Customer Ready System integration.